diff options
| -rw-r--r-- | arch/x86/kernel/entry_64.S | 6 | ||||
| -rw-r--r-- | arch/x86/kernel/signal_32.c | 3 | ||||
| -rw-r--r-- | arch/x86/kernel/signal_64.c | 3 | ||||
| -rw-r--r-- | include/asm-x86/thread_info_32.h | 2 | ||||
| -rw-r--r-- | include/asm-x86/thread_info_64.h | 5 | ||||
| -rw-r--r-- | include/linux/hrtimer.h | 9 | ||||
| -rw-r--r-- | include/linux/sched.h | 3 | ||||
| -rw-r--r-- | kernel/Kconfig.hz | 2 | ||||
| -rw-r--r-- | kernel/sched.c | 210 | ||||
| -rw-r--r-- | kernel/sched_fair.c | 69 | ||||
| -rw-r--r-- | kernel/sched_idletask.c | 2 | ||||
| -rw-r--r-- | kernel/sched_rt.c | 2 |
12 files changed, 295 insertions, 21 deletions
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 3a058bb..e70f388 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -283,7 +283,7 @@ sysret_careful: sysret_signal: TRACE_IRQS_ON sti - testl $(_TIF_SIGPENDING|_TIF_SINGLESTEP|_TIF_MCE_NOTIFY),%edx + testl $_TIF_DO_NOTIFY_MASK,%edx jz 1f /* Really a signal */ @@ -377,7 +377,7 @@ int_very_careful: jmp int_restore_rest int_signal: - testl $(_TIF_SIGPENDING|_TIF_SINGLESTEP|_TIF_MCE_NOTIFY),%edx + testl $_TIF_DO_NOTIFY_MASK,%edx jz 1f movq %rsp,%rdi # &ptregs -> arg1 xorl %esi,%esi # oldset -> arg2 @@ -603,7 +603,7 @@ retint_careful: jmp retint_check retint_signal: - testl $(_TIF_SIGPENDING|_TIF_SINGLESTEP|_TIF_MCE_NOTIFY),%edx + testl $_TIF_DO_NOTIFY_MASK,%edx jz retint_swapgs TRACE_IRQS_ON sti diff --git a/arch/x86/kernel/signal_32.c b/arch/x86/kernel/signal_32.c index 9bdd830..20f29e4 100644 --- a/arch/x86/kernel/signal_32.c +++ b/arch/x86/kernel/signal_32.c @@ -658,6 +658,9 @@ void do_notify_resume(struct pt_regs *regs, void *_unused, /* deal with pending signal delivery */ if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK)) do_signal(regs); + + if (thread_info_flags & _TIF_HRTICK_RESCHED) + hrtick_resched(); clear_thread_flag(TIF_IRET); } diff --git a/arch/x86/kernel/signal_64.c b/arch/x86/kernel/signal_64.c index ab086b0..38d8064 100644 --- a/arch/x86/kernel/signal_64.c +++ b/arch/x86/kernel/signal_64.c @@ -480,6 +480,9 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags) /* deal with pending signal delivery */ if (thread_info_flags & (_TIF_SIGPENDING|_TIF_RESTORE_SIGMASK)) do_signal(regs); + + if (thread_info_flags & _TIF_HRTICK_RESCHED) + hrtick_resched(); } void signal_fault(struct pt_regs *regs, void __user *frame, char *where) diff --git a/include/asm-x86/thread_info_32.h b/include/asm-x86/thread_info_32.h index 22a8cbc..ef58fd2 100644 --- a/include/asm-x86/thread_info_32.h +++ b/include/asm-x86/thread_info_32.h @@ -132,6 +132,7 @@ static inline struct thread_info *current_thread_info(void) #define TIF_SYSCALL_AUDIT 6 /* syscall auditing active */ #define TIF_SECCOMP 7 /* secure computing */ #define TIF_RESTORE_SIGMASK 8 /* restore signal mask in do_signal() */ +#define TIF_HRTICK_RESCHED 9 /* reprogram hrtick timer */ #define TIF_MEMDIE 16 #define TIF_DEBUG 17 /* uses debug registers */ #define TIF_IO_BITMAP 18 /* uses I/O bitmap */ @@ -147,6 +148,7 @@ static inline struct thread_info *current_thread_info(void) #define _TIF_SYSCALL_AUDIT (1<<TIF_SYSCALL_AUDIT) #define _TIF_SECCOMP (1<<TIF_SECCOMP) #define _TIF_RESTORE_SIGMASK (1<<TIF_RESTORE_SIGMASK) +#define _TIF_HRTICK_RESCHED (1<<TIF_HRTICK_RESCHED) #define _TIF_DEBUG (1<<TIF_DEBUG) #define _TIF_IO_BITMAP (1<<TIF_IO_BITMAP) #define _TIF_FREEZE (1<<TIF_FREEZE) diff --git a/include/asm-x86/thread_info_64.h b/include/asm-x86/thread_info_64.h index beae2bf..7f6ee68 100644 --- a/include/asm-x86/thread_info_64.h +++ b/include/asm-x86/thread_info_64.h @@ -115,6 +115,7 @@ static inline struct thread_info *stack_thread_info(void) #define TIF_SECCOMP 8 /* secure computing */ #define TIF_RESTORE_SIGMASK 9 /* restore signal mask in do_signal */ #define TIF_MCE_NOTIFY 10 /* notify userspace of an MCE */ +#define TIF_HRTICK_RESCHED 11 /* reprogram hrtick timer */ /* 16 free */ #define TIF_IA32 17 /* 32bit process */ #define TIF_FORK 18 /* ret_from_fork */ @@ -133,6 +134,7 @@ static inline struct thread_info *stack_thread_info(void) #define _TIF_SECCOMP (1<<TIF_SECCOMP) #define _TIF_RESTORE_SIGMASK (1<<TIF_RESTORE_SIGMASK) #define _TIF_MCE_NOTIFY (1<<TIF_MCE_NOTIFY) +#define _TIF_HRTICK_RESCHED (1<<TIF_HRTICK_RESCHED) #define _TIF_IA32 (1<<TIF_IA32) #define _TIF_FORK (1<<TIF_FORK) #define _TIF_ABI_PENDING (1<<TIF_ABI_PENDING) @@ -146,6 +148,9 @@ static inline struct thread_info *stack_thread_info(void) /* work to do on any return to user space */ #define _TIF_ALLWORK_MASK (0x0000FFFF & ~_TIF_SECCOMP) +#define _TIF_DO_NOTIFY_MASK \ + (_TIF_SIGPENDING|_TIF_SINGLESTEP|_TIF_MCE_NOTIFY|_TIF_HRTICK_RESCHED) + /* flags to check in __switch_to() */ #define _TIF_WORK_CTXSW (_TIF_DEBUG|_TIF_IO_BITMAP) diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h index 7a9398e..ecc8e26 100644 --- a/include/linux/hrtimer.h +++ b/include/linux/hrtimer.h @@ -217,6 +217,11 @@ static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer) return timer->base->get_time(); } +static inline int hrtimer_is_hres_active(struct hrtimer *timer) +{ + return timer->base->cpu_base->hres_active; +} + /* * The resolution of the clocks. The resolution value is returned in * the clock_getres() system call to give application programmers an @@ -248,6 +253,10 @@ static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer) return timer->base->softirq_time; } +static inline int hrtimer_is_hres_active(struct hrtimer *timer) +{ + return 0; +} #endif extern ktime_t ktime_get(void); diff --git a/include/linux/sched.h b/include/linux/sched.h index 7907845c..43e0339 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -257,6 +257,7 @@ extern void trap_init(void); extern void account_process_tick(struct task_struct *task, int user); extern void update_process_times(int user); extern void scheduler_tick(void); +extern void hrtick_resched(void); extern void sched_show_task(struct task_struct *p); @@ -849,7 +850,7 @@ struct sched_class { #endif void (*set_curr_task) (struct rq *rq); - void (*task_tick) (struct rq *rq, struct task_struct *p); + void (*task_tick) (struct rq *rq, struct task_struct *p, int queued); void (*task_new) (struct rq *rq, struct task_struct *p); void (*set_cpus_allowed)(struct task_struct *p, cpumask_t *newmask); diff --git a/kernel/Kconfig.hz b/kernel/Kconfig.hz index 4af15802..526128a 100644 --- a/kernel/Kconfig.hz +++ b/kernel/Kconfig.hz @@ -54,3 +54,5 @@ config HZ default 300 if HZ_300 default 1000 if HZ_1000 +config SCHED_HRTICK + def_bool HIGH_RES_TIMERS && X86 diff --git a/kernel/sched.c b/kernel/sched.c index 6ee3760..17f93d3 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -65,6 +65,7 @@ #include <linux/reciprocal_div.h> #include <linux/unistd.h> #include <linux/pagemap.h> +#include <linux/hrtimer.h> #include <asm/tlb.h> #include <asm/irq_regs.h> @@ -451,6 +452,12 @@ struct rq { struct list_head migration_queue; #endif +#ifdef CONFIG_SCHED_HRTICK + unsigned long hrtick_flags; + ktime_t hrtick_expire; + struct hrtimer hrtick_timer; +#endif + #ifdef CONFIG_SCHEDSTATS /* latency stats */ struct sched_info rq_sched_info; @@ -572,6 +579,8 @@ enum { SCHED_FEAT_START_DEBIT = 4, SCHED_FEAT_TREE_AVG = 8, SCHED_FEAT_APPROX_AVG = 16, + SCHED_FEAT_HRTICK = 32, + SCHED_FEAT_DOUBLE_TICK = 64, }; const_debug unsigned int sysctl_sched_features = @@ -579,7 +588,9 @@ const_debug unsigned int sysctl_sched_features = SCHED_FEAT_WAKEUP_PREEMPT * 1 | SCHED_FEAT_START_DEBIT * 1 | SCHED_FEAT_TREE_AVG * 0 | - SCHED_FEAT_APPROX_AVG * 0; + SCHED_FEAT_APPROX_AVG * 0 | + SCHED_FEAT_HRTICK * 1 | + SCHED_FEAT_DOUBLE_TICK * 0; #define sched_feat(x) (sysctl_sched_features & SCHED_FEAT_##x) @@ -796,6 +807,173 @@ void sched_clock_idle_wakeup_event(u64 delta_ns) } EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event); +static void __resched_task(struct task_struct *p, int tif_bit); + +static inline void resched_task(struct task_struct *p) +{ + __resched_task(p, TIF_NEED_RESCHED); +} + +#ifdef CONFIG_SCHED_HRTICK +/* + * Use HR-timers to deliver accurate preemption points. + * + * Its all a bit involved since we cannot program an hrt while holding the + * rq->lock. So what we do is store a state in in rq->hrtick_* and ask for a + * reschedule event. + * + * When we get rescheduled we reprogram the hrtick_timer outside of the + * rq->lock. + */ +static inline void resched_hrt(struct task_struct *p) +{ + __resched_task(p, TIF_HRTICK_RESCHED); +} + +static inline void resched_rq(struct rq *rq) +{ + unsigned long flags; + + spin_lock_irqsave(&rq->lock, flags); + resched_task(rq->curr); + spin_unlock_irqrestore(&rq->lock, flags); +} + +enum { + HRTICK_SET, /* re-programm hrtick_timer */ + HRTICK_RESET, /* not a new slice */ +}; + +/* + * Use hrtick when: + * - enabled by features + * - hrtimer is actually high res + */ +static inline int hrtick_enabled(struct rq *rq) +{ + if (!sched_feat(HRTICK)) + return 0; + return hrtimer_is_hres_active(&rq->hrtick_timer); +} + +/* + * Called to set the hrtick timer state. + * + * called with rq->lock held and irqs disabled + */ +static void hrtick_start(struct rq *rq, u64 delay, int reset) +{ + assert_spin_locked(&rq->lock); + + /* + * preempt at: now + delay + */ + rq->hrtick_expire = + ktime_add_ns(rq->hrtick_timer.base->get_time(), delay); + /* + * indicate we need to program the timer + */ + __set_bit(HRTICK_SET, &rq->hrtick_flags); + if (reset) + __set_bit(HRTICK_RESET, &rq->hrtick_flags); + + /* + * New slices are called from the schedule path and don't need a + * forced reschedule. + */ + if (reset) + resched_hrt(rq->curr); +} + +static void hrtick_clear(struct rq *rq) +{ + if (hrtimer_active(&rq->hrtick_timer)) + hrtimer_cancel(&rq->hrtick_timer); +} + +/* + * Update the timer from the possible pending state. + */ +static void hrtick_set(struct rq *rq) +{ + ktime_t time; + int set, reset; + unsigned long flags; + + WARN_ON_ONCE(cpu_of(rq) != smp_processor_id()); + + spin_lock_irqsave(&rq->lock, flags); + set = __test_and_clear_bit(HRTICK_SET, &rq->hrtick_flags); + reset = __test_and_clear_bit(HRTICK_RESET, &rq->hrtick_flags); + time = rq->hrtick_expire; + clear_thread_flag(TIF_HRTICK_RESCHED); + spin_unlock_irqrestore(&rq->lock, flags); + + if (set) { + hrtimer_start(&rq->hrtick_timer, time, HRTIMER_MODE_ABS); + if (reset && !hrtimer_active(&rq->hrtick_timer)) + resched_rq(rq); + } else + hrtick_clear(rq); +} + +/* + * High-resolution timer tick. + * Runs from hardirq context with interrupts disabled. + */ +static enum hrtimer_restart hrtick(struct hrtimer *timer) +{ + struct rq *rq = container_of(timer, struct rq, hrtick_timer); + + WARN_ON_ONCE(cpu_of(rq) != smp_processor_id()); + + spin_lock(&rq->lock); + __update_rq_clock(rq); + rq->curr->sched_class->task_tick(rq, rq->curr, 1); + spin_unlock(&rq->lock); + + return HRTIMER_NORESTART; +} + +static inline void init_rq_hrtick(struct rq *rq) +{ + rq->hrtick_flags = 0; + hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); + rq->hrtick_timer.function = hrtick; + rq->hrtick_timer.cb_mode = HRTIMER_CB_IRQSAFE_NO_SOFTIRQ; +} + +void hrtick_resched(void) +{ + struct rq *rq; + unsigned long flags; + + if (!test_thread_flag(TIF_HRTICK_RESCHED)) + return; + + local_irq_save(flags); + rq = cpu_rq(smp_processor_id()); + hrtick_set(rq); + local_irq_restore(flags); +} +#else +static inline void hrtick_clear(struct rq *rq) +{ +} + +static inline void hrtick_set(struct rq *rq) +{ +} + +static inline void init_rq_hrtick(struct rq *rq) +{ +} + +void hrtick_resched(void) +{ +} +#endif + /* * resched_task - mark a task 'to be rescheduled now'. * @@ -809,16 +987,16 @@ EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event); #define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG) #endif -static void resched_task(struct task_struct *p) +static void __resched_task(struct task_struct *p, int tif_bit) { int cpu; assert_spin_locked(&task_rq(p)->lock); - if (unlikely(test_tsk_thread_flag(p, TIF_NEED_RESCHED))) + if (unlikely(test_tsk_thread_flag(p, tif_bit))) return; - set_tsk_thread_flag(p, TIF_NEED_RESCHED); + set_tsk_thread_flag(p, tif_bit); cpu = task_cpu(p); if (cpu == smp_processor_id()) @@ -841,10 +1019,10 @@ static void resched_cpu(int cpu) spin_unlock_irqrestore(&rq->lock, flags); } #else -static inline void resched_task(struct task_struct *p) +static void __resched_task(struct task_struct *p, int tif_bit) { assert_spin_locked(&task_rq(p)->lock); - set_tsk_need_resched(p); + set_tsk_thread_flag(p, tif_bit); } #endif @@ -3497,7 +3675,7 @@ void scheduler_tick(void) rq->tick_timestamp = rq->clock; update_cpu_load(rq); if (curr != rq->idle) /* FIXME: needed? */ - curr->sched_class->task_tick(rq, curr); + curr->sched_class->task_tick(rq, curr, 0); spin_unlock(&rq->lock); #ifdef CONFIG_SMP @@ -3643,6 +3821,8 @@ need_resched_nonpreemptible: schedule_debug(prev); + hrtick_clear(rq); + /* * Do the rq-clock update outside the rq lock: */ @@ -3680,14 +3860,20 @@ need_resched_nonpreemptible: ++*switch_count; context_switch(rq, prev, next); /* unlocks the rq */ + /* + * the context switch might have flipped the stack from under + * us, hence refresh the local variables. + */ + cpu = smp_processor_id(); + rq = cpu_rq(cpu); } else spin_unlock_irq(&rq->lock); - if (unlikely(reacquire_kernel_lock(current) < 0)) { - cpu = smp_processor_id(); - rq = cpu_rq(cpu); + hrtick_set(rq); + + if (unlikely(reacquire_kernel_lock(current) < 0)) goto need_resched_nonpreemptible; - } + preempt_enable_no_resched(); if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) goto need_resched; @@ -6913,6 +7099,8 @@ void __init sched_init(void) rq->rt.overloaded = 0; rq_attach_root(rq, &def_root_domain); #endif + init_rq_hrtick(rq); + atomic_set(&rq->nr_iowait, 0); array = &rq->rt.active; diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index dfa18d5..3dab1ff 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -642,13 +642,29 @@ static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev) cfs_rq->curr = NULL; } -static void entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr) +static void +entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued) { /* * Update run-time statistics of the 'current'. */ update_curr(cfs_rq); +#ifdef CONFIG_SCHED_HRTICK + /* + * queued ticks are scheduled to match the slice, so don't bother + * validating it and just reschedule. + */ + if (queued) + return resched_task(rq_of(cfs_rq)->curr); + /* + * don't let the period tick interfere with the hrtick preemption + */ + if (!sched_feat(DOUBLE_TICK) && + hrtimer_active(&rq_of(cfs_rq)->hrtick_timer)) + return; +#endif + if (cfs_rq->nr_running > 1 || !sched_feat(WAKEUP_PREEMPT)) check_preempt_tick(cfs_rq, curr); } @@ -754,6 +770,43 @@ static inline struct sched_entity *parent_entity(struct sched_entity *se) #endif /* CONFIG_FAIR_GROUP_SCHED */ +#ifdef CONFIG_SCHED_HRTICK +static void hrtick_start_fair(struct rq *rq, struct task_struct *p) +{ + int requeue = rq->curr == p; + struct sched_entity *se = &p->se; + struct cfs_rq *cfs_rq = cfs_rq_of(se); + + WARN_ON(task_rq(p) != rq); + + if (hrtick_enabled(rq) && cfs_rq->nr_running > 1) { + u64 slice = sched_slice(cfs_rq, se); + u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime; + s64 delta = slice - ran; + + if (delta < 0) { + if (rq->curr == p) + resched_task(p); + return; + } + + /* + * Don't schedule slices shorter than 10000ns, that just + * doesn't make sense. Rely on vruntime for fairness. + */ + if (!requeue) + delta = max(10000LL, delta); + + hrtick_start(rq, delta, requeue); + } +} +#else +static inline void +hrtick_start_fair(struct rq *rq, struct task_struct *p) +{ +} +#endif + /* * The enqueue_task method is called before nr_running is * increased. Here we update the fair scheduling stats and @@ -782,6 +835,8 @@ static void enqueue_task_fair(struct rq *rq, struct task_struct *p, int wakeup) */ if (incload) inc_cpu_load(rq, topse->load.weight); + + hrtick_start_fair(rq, rq->curr); } /* @@ -814,6 +869,8 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int sleep) */ if (decload) dec_cpu_load(rq, topse->load.weight); + + hrtick_start_fair(rq, rq->curr); } /* @@ -1049,6 +1106,7 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p) static struct task_struct *pick_next_task_fair(struct rq *rq) { + struct task_struct *p; struct cfs_rq *cfs_rq = &rq->cfs; struct sched_entity *se; @@ -1060,7 +1118,10 @@ static struct task_struct *pick_next_task_fair(struct rq *rq) cfs_rq = group_cfs_rq(se); } while (cfs_rq); - return task_of(se); + p = task_of(se); + hrtick_start_fair(rq, p); + + return p; } /* @@ -1235,14 +1296,14 @@ move_one_task_fair(struct rq *this_rq, int this_cpu, struct rq *busiest, /* * scheduler tick hitting a task of our scheduling class: */ -static void task_tick_fair(struct rq *rq, struct task_struct *curr) +static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued) { struct cfs_rq *cfs_rq; struct sched_entity *se = &curr->se; for_each_sched_entity(se) { cfs_rq = cfs_rq_of(se); - entity_tick(cfs_rq, se); + entity_tick(cfs_rq, se, queued); } } diff --git a/kernel/sched_idletask.c b/kernel/sched_idletask.c index ef7a266..2bcafa3 100644 --- a/kernel/sched_idletask.c +++ b/kernel/sched_idletask.c @@ -61,7 +61,7 @@ move_one_task_idle(struct rq *this_rq, int this_cpu, struct rq *busiest, } #endif -static void task_tick_idle(struct rq *rq, struct task_struct *curr) +static void task_tick_idle(struct rq *rq, struct task_struct *curr, int queued) { } diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c index f350f7b..83fbbcb 100644 --- a/kernel/sched_rt.c +++ b/kernel/sched_rt.c @@ -863,7 +863,7 @@ static void watchdog(struct rq *rq, struct task_struct *p) } } -static void task_tick_rt(struct rq *rq, struct task_struct *p) +static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued) { update_curr_rt(rq); |
